Selecting a suitable battery technology for the photovoltaic battery integrated module

The use of batteries is indispensable in stand-alone photovoltaic (PV) systems, and the physical integration of a battery pack and a PV panel in one device enables this concept while easing the installation and system scaling. However, the influence of high temperatures is one of the main challenges of placing a solar panel close to a battery pack. Therefore, this paper aims to select a suitable battery technology considering the temperature of operation and the expected current profiles. The methodology for battery selection is composed of a literature review, an integrated model, the design of an application-based testing, and the execution of the aging test. The integrated model was employed to choose among the battery technologies, and to design a testing procedure that simulated the operational conditions of the PV-battery Integrated Module (PBIM). Two Li-ion pouch cells were tested at two representative temperatures while applying various charging/discharging profiles. After the testing, the LiFePO4 (LFP) cells showed better performance when compared to LiCoO2 batteries (LCO), where for instance, the LCO cells capacity tested at 45 degrees C, faded 2,45% more than the LFP cells at the same testing conditions. Therefore, LFP cells are selected as a suitable option to be part of the PBIM.